1. Field of the Invention
This invention relates to a system for cooling the hot parts of a gas turbine engine and more particularly to structure of the gas turbine engine defining a fluid flow path for delivering a coolant through the stator blades to an inner chamber for distribution into a main coolant flow directed to the rotor disc and blade roots and a secondary sealing fluid flow which is thereafter isolated from the coolant flow.
2. Description of the Prior Art
The invention generally provides a system for supplying cooling fluid such as air or steam to the rotor and root area of the rotor blade as shown in U.S. Pat. Nos. 3,602,605 and 3,647,311, both having a common assignee to the present invention. However, more particularly, the present invention is an improvement of the system disclosed in commonly assigned U.S. Pat. No. 3,945,758. In the last-mentioned patent, air, primarily used for cooling, is delivered through the stator vanes to an air box radially inwardly of the vanes. Thereupon, the air is divided: one portion flowing into an inner cavity between adjacent shoulders of adjacent rotor discs; another portion flows outwardly through a lip seal to prevent the hot motive fluid from flowing into the air box; and also a portion flowing through a series of seal rings disposed between the stator and the rotor. This last-mentioned flow is heated due to friction as it flows through the sealing structure, and is reintroduced into the cooling airflow just prior to the cooling flow entering the cavity between rotor discs for distribution to the blade root of the next downstream blade row. Such leakage of the sealing air raises the temperature of the cooling fluid and thereby decreases its cooling effectiveness.